1. Field of the Invention
The present invention relates in general to the field of Missiles and Munitions used by the Armed Forces, and it particularly relates to a new design method for a fin deployment system that enables a substantial reduction in the volume of munitions as compared to those employing conventional fin deployment systems. More specifically, the present invention incorporates a novel wrap-around fin concept that is capable of achieving a straight fin deployment which is necessary in maintaining a proper roll control authority during flight while substantially reducing the volume, hence weight, of missiles and munitions. The volume reduction thus translates into significant tactical advantages of these new missiles and munitions incorporating the present invention by enabling more electronic payload or lethality to be packaged into the volume savings.
2. Background of the Invention
High explosive missiles and munitions are an essential part of the arsenals of the Armed Forces. Missiles and munitions are highly complex systems generally used for deploying projectiles capable of high-speed and long-range maneuvers to deliver lethality to a target or to intercept an incoming threat. A missile projectile is normally discharged by means of a gun tube, or a missile launcher, or the like. Upon exiting a muzzle of a gun tube, the projectile gains a rapid increase in speed and altitude. At a high speed flight, the trajectory and stability of a missile projectile are actively controlled by navigation and guidance electronics to operate various control surfaces such as fins and canards.
Fins are control surfaces generally deployed in the aft of a missile projectile to provide roll stability during flight. On the other hand, canards are control surfaces typically mounted in front of a missile projectile to enhance its maneuverability. Fins are normally deployed lengthwise and with a circular symmetry with respect to the projectile body to minimize asymmetric aerodynamic loading which can adversely affect the stability of the projectile. To provide a control authority, fins are constructed with hinges to allow them to be actuated individually so as to modify the aerodynamic forces on the projectile for guidance purposes.
A conventional missile projectile typically employs a fin deployment system that is housed within the projectile body and rotated perpendicular to the projectile body axis. Upon exiting a gun muzzle, the fins are activated to open up lengthwise on the projectile body to provide the roll stability. A conventional fin deployment system occupies a significant interior volume of the projectile body. For example, the boom part of a 105 mm tank projectile, which is the portion of the projectile body containing the fin deployment system, is typically about 8 inches in length and weighs approximately 11 lbs. This represents a 25% of the total volume of the projectile body. The volume taken up by a conventional fin deployment system generally is viewed as a non-utilizable space within a projectile body that could otherwise be used for carrying additional volume of warheads or other explosive materials as well as electronics packages such as guidance and control electronics. Therefore, it is a well-known design objective to minimize the take-up volume of the fin deployment system by alternate design methodologies.
Attempts to improve a fin deployment system for missiles and munitions have been considered. One such exemplary methodology utilizes a wrap-around fin deployment system on the 2.75-inch rockets. The wrap-around fin deployment system is housed in the exterior of the projectile body with the fins folded circumferentially around a center body. In theory, this conventional design is able to reduce the take-up volume of the fin deployment system. In practice, problems with this conventional fin deployment system have been encountered whereby the deployed fins have curved surfaces upon deploying from their housing, the fin itself is shaped to the profile of the missile projectile for a semi-circular fin shape. The curved fins can significantly compromise the roll control authority of a missile projectile, which is not an issue on non guided systems. Roll control authority is needed for guided missile projectile systems; therefore the deployment system used by the 2.75 inch rocket is not viable.
Thus, it is realized that the current attempts to provide a fin deployment systems that can achieve a considerable projectile volume savings while maintaining a good roll control authority heretofore remains unfulfilled. Consequently, it is therefore recognized that a further enhancement in the design methodology for a fin deployment system is still needed to achieve the foregoing objectives. Preferably, the new design methodology would provide a space saving fin deployment system capable of deploying straight fins to maintain a good roll control authority while achieving the design objective of reducing the volume of the projectile taken up by the fin deployment system.